Significant reductions in vehicle emissions can be achieved, congestion can be limited, safety can be enhanced and travel times reduced by integrating diverse technology in the vehicular transportation domain. Numerous schemes have been proposed in the past for informing drivers of traffic conditions and presenting them with proposed alternatives when congestion is found. For example, traffic helicopters have been used for decades by radio stations to spot areas of congestion and suggest alternate paths that drivers may wish to consider.
With the growing popularity of GPS and hand-held computing devices, particularly those connected to cellular networks or the internet, other approaches have been used, such as graphical representations of maps with routes being color-coded to indicate levels of congestion.
Another approach to the traffic congestion problem involves “smart” traffic signals (sometimes referred to as traffic lights). For instance, railroad crossings have for decades been tied to traffic signals to help ease the flow of traffic on routes adjacent to railroad crossings when a train approaches. Further, certain systems have been installed that allow emergency vehicles such as fire trucks to change the state of a light from red to green so that the emergency vehicle can cross the intersection quickly with, rather than against, the signal.
In still another related area, various attempts have been made to collect traffic information from drivers who have, for example, GPS-enabled smartphones with them in their vehicles. Systems are emerging that take advantage of the integration of technologies that are available to report traffic information to drivers and suggest routes based on that information, to communicate with traffic signals, and to collect traffic information from drivers. Examples of such systems are disclosed in U.S. Pat. No. 9,852,624, filed as application Ser. No. 15/076,116 on Mar. 21, 2016, entitled “Network Security System with Application for Driver Safety System,” the contents of which are incorporated herein by reference as if fully set forth herein.
Further, it has now become commonplace for traffic controls (such as traffic signals) to be networked with a centralized control facility. In this manner, the control facility may both direct operations of traffic signals and, for signals that operate autonomously, receive from the signals indications of their current state (green, amber, red) and expected time of transition to a new state, e.g., current green state will transition to red state (via intermediate transition to amber state) at 10:17:13.3 a.m. local time. Some municipalities even publish for public use such timing and related data. See, e.g., the aforementioned U.S. Pat. No. 9,852,624.
However, such information is not universally available. In some municipalities, such data either do not exist or are not provided for use outside the municipality's public works department or equivalent. In such situations, it would be helpful to determine states of traffic signals independently. One such method is taught in U.S. Patent Publication US 2018/0075739, entitled “Traffic Routing Display System with Multiple Signal Lookahead,” the contents of which are incorporated by reference as if fully set forth herein. In that application, images from public webcams are analyzed to identify traffic signals and to obtain from such images indications of the states of such traffic signals.
Some effort has been made to use GPS-detected movement of vehicles to determine when traffic signals are green, and to make assumptions regarding timing of other signals (e.g., similar timing cycles), in order to identify specific timing plans that match best with observations. For example, U.S. Patent Publication US 2015/0120175 uses estimates of average acceleration and deceleration of vehicles approaching and departing from traffic signals to help estimate signal phase durations. See also related paper entitled, CROWDSOURCING PHASE AND TIMING OF PRE-TIMED TRAFFIC SIGNALS IN PRESENCE OF QUEUES: ALGORITHMS AND BACKEND SYSTEM ARCHITECTURE, S. Alireza Fayazi and Ardlalan Vehidi, Clemson University, Clemson, S.C., available at http://alirezafayazi.com/docs/07323843.pdf.
For various reasons observations of traffic movement do not, in reality, closely correspond to the specific time that a signal turns green. Traffic signal transition times derived from these observations often differ from reality by three seconds or more, and for many applications (e.g., routing decisions and speed recommendations) such differences are significant. Thus, it would be advantageous to have additional methods and systems for determining states of traffic signals, for instance for use by driver safety systems as described herein.
In one particular area addressed by this disclosure, it would be advantageous to use communications from existing user devices such as smartphones to provide sufficient information to a remote processor to allow accurate estimations to be made of when a particular traffic signal transitions, e.g., from red to green.